1. Field
The invention is a grinding apparatus for refacing frusto-conical valve faces, such as those on the valve heads of internal combustion engine valves in passenger vehicles and trucks, in the range of three-fourths to four inches head diameter.
2. Related Art
Grinding of internal combustion engine valve faces has long been a procedure in reconditioning engines such as those in passenger vehicles and trucks. Traditionally, apparatus for valve face grinding or resurfacing has included a grinding wheel with an abrasive cylindrical grinding surface and a workhead for mounting or holding the valve by its stem. The workhead has been manually actuated to grip and release the valve stem of the valve to be ground. Such apparatus is disclosed in the U.S. Pat. No. to Gagne et al. - 2,136,188. Such apparatus has been made and sold in the U.S. by K.0. Lee Company, Aberdeen, S. Dak., the assignee of the present invention, designated as valve refacers, Model Nos. K 403 Series and Model K 500 HM2 (heavy duty).
Such devices require frequent dressing of the grinding wheel, such as dressing after grinding fifteen to twenty valves, and significant time is also required to manually release a ground or refaced valve and insert and grip an unground valve. These time requirements become increasingly significant as the number of valves to be ground increases.
Other patents, not in the valve grinding art, such as the U.S. Pat. No. to Chaplik - 2,802,310, disclose grinding a hypodermic needle point which is gripped by manual clamping in a work head, and moved into grinding engagement with an endless abrasive belt. In Chaplik there is no need for or disclosure of any means for rotating the hypodermic needle point against the endless belt, which would be counter-productive in that a sharp point would be ground away by rotation of the needle, and there is no teaching of an automatically actuated gripping and/or release mechanism for gripping and releasing the needle in the workhead.
The U.S. Pat. No. to Erani - 4,662,116 teaches the substitution or interchangeability of an endless belt grinder for a grinding wheel or disc. Erani does not, however, teach any work head mechanism for mounting and rotating the work piece, such as a valve stem and head, as does the present invention.
Neither Chaplik, nor Erani could be used to grind or reface the frusto-conical valve face of valves used in internal combustion engines.